Various attempts have been made to use materials containing copper and boron as components in nuclear waste disposal systems. Copper is a metal of choice because of its high thermal conductivity and high melting point. Boron is used because of its capability to absorb neutron radiation.
The use of copper-boron composites as components in nuclear waste disposal systems is noted in U.S. Pat. No. 4,227,928 which issued to Wang on Oct. 14, 1980. This patent discloses the use of boron carbide filled copper plate material used to line baskets for containing nuclear waste material. The Wang patent covers a process for manufacturing the plate material by electroless copper process for manufacturing the plate material by electroless copper plating particulate boron carbide core material and then electrolytically depositing additional copper on to the particles. The copper encapsulated boron carbide particles are then hot rolled, hot pressed or cold pressed and sintered to produce boron carbide filled copper shields.
A material presently used as a neutron absorber in nuclear waste containment vessels designed for the temporary storage of nuclear waste is a commercial composite material consisting of an aluminum matrix with 1.8 weight percent boron. The material is not considered a viable candidate for long term, permanent waste disposal systems because of inherently poor thermal conductivity and low strength.
Borated stainless steel is a material currently used for neutron absorption in long term nuclear waste storage containers. This material contains approximately 0.2 to 2.25 weight percent boron. While the borated stainless steel material has higher strength than the borated aluminum material, it suffers from inherently poor thermal conductivity. Unlike these known materials, the inventive material has both high strength and high thermal conductivity.
Various methods of manufacturing copper-boron alloys for purposes other than nuclear waste containment are also known to the art. For instance, U.S. Pat. No. 2,964,397, which issued to Cooper on Dec. 13, 1960, discloses copper-boron alloys produced by vacuum melting and high temperature combination of elemental copper and boron particulates.
Additionally, U.S. Pat. No. 3,144,327, which issued to Schmidt, et al. on Aug. 11, 1964, discloses copper-boron alloys produced by combining particulate elemental boron and copper under condition of high temperature and pressure.
It is also known to produce copper-boron alloys by: 1) mechanical alloying of copper-transition metal-carbon particulates whereby transition metal carbides are formed at elevated temperature for the purpose of strengthening the copper matrix, and 2) the high temperature infiltration of a tungsten skeleton with a copper-boron alloy to produce tungsten borides for the purpose of wear resistance.